[bug #58300] GRUB refuses to boot a 32-bit kernel when in EFI mode

[Hamish McIntyre-Bhatty]

URL:
  <https://savannah.gnu.org/bugs/?58300>

                 Summary: GRUB refuses to boot a 32-bit kernel when in EFI
mode
                 Project: GNU GRUB
            Submitted by: hamishmb
            Submitted on: Mon 04 May 2020 11:12:15 AM UTC
                Category: Booting
                Severity: Major
                Priority: 5 - Normal
              Item Group: Software Error
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: Hamish McIntyre-Bhatty
        Originator Email: address@hidden
             Open/Closed: Open
                 Release: 
                 Release: 2.02
         Discussion Lock: Any
         Reproducibility: Every Time
         Planned Release: None

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Details:

Note that this is with BIOS and UEFI images created from Ubuntu 18.04's
current version of GRUB (*2.02-2ubuntu8.15*). If it would be more useful for
me to submit for Ubuntu instead/as well then I'll do that.

GRUB2 fails to boot a 32-bit kernel when started in EFI mode (64-bit EFI) on a
64-bit x86 CPU, and gives the message:

"error: kernel doesn't support 64-bit CPUs"

However, when a bios grub image made by the same version of grub is used, with
the same kernel, on the same CPU, everything is normal and the kernel boots as
expected.

Hence, I know this kernel will boot on a 64-bit CPU, and with a previous
version of GRUB 2 (unfortunately I don't know which version), it also booted
fine in 64-bit mode using GRUB-EFI.

Running with debug=all doesn't seem to provide any extra useful information,
as far as I can tell - it just lists sectors being read and then freed.

Any ideas as to what's going on?




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